﻿/*
 * Copyright 2014 - 2017 Adaptive Financial Consulting Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0S
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using Adaptive.Agrona;

namespace Adaptive.Aeron
{
    /// <summary>
    /// Supplies the reserved value field for a data frame header. The returned value will be set in the header as
    /// <seealso cref="ByteOrder.LittleEndian"/> format.
    /// <para>
    /// This will be called as the last action of encoding a data frame right before the length is set. All other fields
    /// in the header plus the body of the frame will have been written at the point of supply.
    /// </para>
    /// <para>
    /// The reserved value can be used for carrying out of band data with message fragments such a checksums or timestamps.
    /// </para>
    /// 
    /// Callback to provide the reserved value to be encoded with each message fragment as the last action
    /// before the length field is set which commits the fragment for sending to the media.
    /// </summary>
    /// <param name="termBuffer">  containing the encoding message fragment. </param>
    /// <param name="termOffset">  at which the header of the frame begins. </param>
    /// <param name="frameLength"> Total length of the frame including header. </param>
    /// <returns> the value to be used for storing in the reserved value field. </returns>
    public delegate long ReservedValueSupplier(IDirectBuffer termBuffer, int termOffset, int frameLength);
}